CC Nov 2016 Elevated INR

Section

Question

Answer

The ability of oral vitamin K antagonist such as warfarin (Coumadin) to reduce systemic thromboembolic events by inhibiting the biosynthesis of factors ____, _____, ______, and _____ has led to widespread use in the United States?

II, VII, IX, X

Define INR?

it is the most common test for frequent monitoring of the degree of anticoagulation

Studies have shown, however, that even in specialized centers, patients only spend ____% of their time within the desired therapeutic range?

60%

The risk of bleeding approximately doubles for each point increase in the INR above ____?

3.0

*** List several options when the INR is supra-therapeutic? What are the reasons that the basis of the decision to choose a particular strategy?

1) observation, dose adjustment, administration of vitamin K, administration of a coagulation reversal product 2) depends on the level of INR elevation and the presence or absence of bleeding

What should be done for patients who are not bleeding but has a supra-therapeutic INR?

withhold warfarin and monitor the INR until it falls into the desired range

Patients with very high INR (even symptomatic) are not appropriate candidates for what approach?

What medication is the first line pharmacological option for patients with an elevated INR > 10.0 and no significant bleeding if those with serious bleeding regardless of the level of INR elevation because warfarin antagonizes the vitamin K-dependent factors?

vitamin K

Compare IV and oral vitamin K?

1) IV vitamin K works more quickly than oral administration but results are similar after 24 hours of use 2) IV formulation usually begins working within the 2 hours and achieves full effect in 24 hours if hepatic function is normal

The risk of ______ is lower with newer IV formulations compared with historically available options?

anaphylaxis

Why is subcutaneous administration of vitamin K not recommended?

due to its unpredictable effects on the INR

Oral vitamin K is easy to administer and may be used in the outpatient setting, it does not produce what 2 conditions?

1) warfarin resistance. 2) anaphylactic reactions

*** List the circumstances when 4-factor prothrombin complex concentrate (PCC) should be administered?

when significant bleeding is present and this is defined as life-threatening hemorrhage (intracranial) requiring hospitalization or bleeding leading to a decrease in hgb >2.0 g/dL, requiring transfusion of > 2 units packed red blood cells or resulting in surgical/ procedural intervention

What are the alternatives for 4-factor prothrombin complex concentrate?

1) FFP has a disadvantage of potential allergic reactions and transmission of infection, longer preparation time and higher volume 2) 4-factor PCC and recombinant factor VIIa are more concentrated, with less infection transmission risk

Why is factor VIIa least preferred by some authors?

it does not provide the other vitamin K-dependent factors that are affected by warfarin

The above 3 products are more rapid in onset than vitamin &, although the effect is temporary (up to 24 hours), so when are these products considered?

For short-term bridge until vitamin K is effective

After addressing the elevated INR, what is the next step?

a careful determination as to why the level of anticoagulation is increased

Warfarin interacts with a variety of drugs and patients should be asked about what?

1)dosage changes, as well as any new medications like herbal and alternative products 2) patient family members should be asked about dietary changes and compliance with warfarin administration 3) consider changes in liver function because progressive liver disease will decrease coagulation factor synthesis

*** SUMMARY = What is the guideline for patients with an elevated INR who are not bleeding?

withhold warfarin and monitor the INR until it falls into the desired range

*** SUMMARY = What medication is recommended for patients with INR > 10.0, even if no bleeding is present?

vitamin K

*** SUMMARY = For patients with significant bleeding (regardless of INR), what should be done?